Mammals of the Soviet Union Vol.II Part 1a, SIRENIA AND CARNIVORA (Sea cows; Wolves and Bears), p. 611, V.G Heptner and N.P Naumov editors, Science Publishers, Inc. USA. 1998. 1-886106-81-9
Calvignac, S.; Hughes, S (1998). «Ancient DNA evidence for the loss of a highly divergent brown bear clade during historical times». Molecular Ecology. 17 (8): 1962–1970. doi:10.1111/j.1365-294x.2008.03631.x. PMID18363668.
Sagør, J.T. (1997). «Compatibility of brown bear Ursus arctos and free-ranging sheep in Norway». Biological Conservation. 81 (1–2): 91–95. doi:10.1016/s0006-3207(96)00165-6.
Calvignac, S.; Hughes, S (1998). «Ancient DNA evidence for the loss of a highly divergent brown bear clade during historical times». Molecular Ecology. 17 (8): 1962–1970. doi:10.1111/j.1365-294x.2008.03631.x. PMID18363668.